Hydraulic control receiver with closing plate

ABSTRACT

A hydraulic receiver for clutch control having a fixed part including an internal guide tube and a concentric external body defining a blind annular cavity supplied with fluid. A piston carrying a drive element for engaging a declutching device is mounted inside the blind annular cavity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns hydraulic receivers, for clutch control,notably in motor vehicles, having a fixed part comprising an internalguide tube and a concentric external body defining a blind annularcavity suitable for being supplied with fluid and inside which there ismounted, so as to be axially movable, a piston carrying a drive elementsuitable for acting on the declutching device of a clutch.

2. Description of the Related Art

Such a receiver, also referred to as a hydraulic receiving cylinder, isdescribed in the document EP-B-0 168 932.

In the latter, the internal guide tube is metallic and projects axiallywith respect to the external body. This tube has at its rear end atransverse plate trapped, in use, between two opposite surfaces formedrespectively on the external body and on a fixed structure to which theexternal body is fixed.

In addition, provision is made for fixing the plate to the body byclamping, as can be seen in FIG. 1 of this document. A static sealingjoint is interposed between the plate and the dorsal face of theexternal body. In use the pressure varies in the cavity delimiting, withthe piston, a variable-volume control chamber.

In certain cases it may be desirable not to grip the plate between thefixed structure and the external body since this makes it necessary toprovide a specific surface on the fixed structure.

In this case it may be thought to use solely a fixing by crimping of theplate onto the metallic external body made of castable material, forexample based on aluminium.

A problem of strength of the fixing is then posed under the effect ofthe pressure variations occurring, in use, in the cavity, knowing thatthe guide tube plate forms the base of this cavity.

In order to do this it may be thought to stiffen the internal peripheryof the plate, for example by means of a rim projecting axially withrespect to the external periphery of the plate. This increases the costof the guide tube.

The object of the present invention is to mitigate these drawbackssimply and economically.

The invention therefore aims to make the fixing of the guide tube to theexternal body more robust. Another aim of the invention is to reduce thecost of the guide tube.

SUMMARY OF THE INVENTION

According to the invention a receiver of the type indicated above, inwhich connection means act between the external body and the guide tubein order to fix the guide tube to the external body, is characterised inthat the base of the blind cavity consist of an internal flange on theexternal body directed radially towards the axis of axial symmetry ofthe guide tube. By virtue of the invention it is not a radial plate onthe guide tube but an internal flange on the external body which issubject in use to the pressure variations during the operations ofdisengaging and engaging the clutch.

This internal flange is more robust so that the connection means areconserved. The fixing of the guide tube to the external body is morerobust, more reliable and more durable.

In addition, the guide tube is conserved because it is the external bodywhich undergoes the pressure variations. The guide tube is less stressedso that the piston slides and therefore moves more precisely andaccurately.

In one embodiment, the connection means act between the internal flangeand the guide tube.

The guide tube being fixed to the internal flange therefore uses lessconsumption of materials since its fixing to the external body takesplace closer to the axis of axial symmetry of the guide tube. The staticsealing joint acting between the external body and the guide tube isalso conserved since it is the internal flange and therefore the solidexternal body which undergoes the pressure variations. This joint ismore economical since it is of smaller size than that of the prior art.

In one embodiment, the fluidtightness and fixing of the guide tube areachieved between the internal periphery of the internal flange and theexternal periphery of the guide tube.

By virtue of these characteristics it is possible for the guide tube tohave no transverse plate and thus be purely tubular in shape. This makesit possible to reduce the costs, as well as the material consumed andthe manufacturing operations. The guide tube is easier to store andhandle. The static sealing joint has the smallest possible size and canbe axially oblong in shape for a better seal.

In one embodiment the joint is mounted in a sealing groove which theinternal flange has at its internal periphery. Naturally, the structurescan be reversed, the groove being formed by pressing in the metallictube.

The connection means can consist of a local upsetting or creeping ofmaterial of the guide tube in a connection groove in the internalflange. The connection groove can be produced at the axially orientedinternal periphery, of the internal flange or in the transverse face,turned in the opposite direction to the cavity, of the internal flange.Thus the fixing is robust and reliable, the internal flange beingthicker than the guide tube.

The connection groove can be merged with the sealing groove, the jointbeing interposed between the bottom of the groove, preferably splayedtowards the guide tube, and the local upsetting of material of the guidetube. This makes it possible to reduce the number of machinings of theexternal body.

As a variant, the connection groove is distinct from the sealing grooveand has a radially oblong shape for receiving an open ring of corrugatedshape radially. The ring is retractable and radially deformable.

The guide tube has a groove opposite the connection groove for partialreception of the corrugated ring. The guide tube is connected to theexternal body by snapping on. By virtue of this arrangement, the guidetube can be symmetrical in shape and have, at its other end, anidentical groove for receiving a circlip or spring ring limiting theaxially movement of the piston with respect to the guide tube.

The two grooves are produced by upsetting material radially in thedirection of the axis of axial symmetry of the guide tube. When theconnection is effected at the transverse face of the internal flange,the guide tube can be immobilised axially by means of a circlip or anut.

In the above, the material of the external body does not undergo anycrimping operation. This body is therefore conserved and can thus bemade from mouldable plastic material. In a variant, the flange made ofmouldable plastic material can be reinforced by means of an insert, forexample metallic.

It will be appreciated that the fixed structure has no need to bemachined in order to offer a bearing surface for the guide tube.

The external body can have, at the rear of the internal flange, ahousing for a rotating joint acting between the external body and arotating shaft, such as the input shaft of the gearbox passing throughthe guide tube, which can surround the rotating joint.

It should be noted that the internal flange is easily obtained bymoulding.

Because the guide tube is conserved, the piston can slide directly onthe guide tube, and can carry at its front end a metallic bearing pieceobtained by pressing.

The piston can be made from synthetic material such as mouldable plasticmaterial reinforced with fibres. Preferably, this material has good slipqualities.

The bearing piece, in one embodiment, serves as a support for a axiallyacting elastically washer, referred to as a self-centring washer,pressing an internal radial flange on one of the ball bearing racewaysin contact with a support section of the bearing piece. The bearingpiece also bears the end of a sealing bellows and a preloading springsurrounded by the bellows.

The ball bearing is intended to cooperate with the declutching deviceand is advantageously fluidtight.

The declutching device can consist of diaphragm fingers forming means ofengaging the clutch or clutch levers distinct from the clutch engagementmeans then consisting of coil springs or a Belleville washer actingbetween the cover and the declutching thrust plate. This clutchmechanism can be provided with a device for taking up wear compensatingat least for the wear on the friction linings of the clutch frictionmember forming part of the clutch.

In a variant, the external body can consist of a large closure plateattached to the casing of a transmission box in order to close theopening of the said box through which an input shaft passes.

The closure plate has an internally hollow protuberance forming part ofthe fixed part of the concentric receiver of the hydraulic clutchcontrol.

The protuberance is advantageously in a single piece with the plate andhas on the inside the internal flange according to the invention.

In one embodiment, the connection means are then offset axially andradially with respect to the static joint.

In another embodiment, the guide tube has a transverse plate directedradially towards the outside and clamped in contact with the rear faceof the transverse flange.

Other advantages will emerge from the following description, with regardto the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a closure plate carrying an internal radialflange according to the invention;

FIG. 2 is a view in section along the line A—A in FIG. 1;

FIG. 3 is a partial view in section to a large scale showing thecoupling of the non-rotating ring of the clutch release bearing to thepiston of the receiver;

FIG. 4 is a partial view, to a large scale, of the clamping of the guidetube;

FIG. 5 is a perspective view of a receiver for a second exampleembodiment;

FIG. 6 is a view in axial section of the receiver of FIG. 5;

FIG. 7 is a partial view of FIG. 6 showing the connection groove;

FIG. 8 is a partial view in axial section of the receiver showing therear thereof as well as another means of connecting the guide tube tothe external body of the concentric receiver;

FIG. 9 is a view similar to FIG. 8 for another example embodiment;

FIG. 10 is a view in section along the line 10 in FIG. 9,

FIGS. 11-13 are views similar to FIG. 8 for other example embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the figures all the elements common to the different embodiments aregiven the same references.

The figures depict the concentric receiver 1 of a hydraulic clutchcontrol comprising, in a known fashion, a sender, the output of which isconnected, via a pipe 2, to a supply input 3 of the receiver 1 providedwith a variable-volume chamber.

A sender is activated in different ways and has a piston 6 movableinside a fixed body 4, 5.

Since it is a case here of an application for a motor vehicle, thesender can be activated by the driver via the clutch pedal.

As a variant the sender can be activated in an assisted fashion, forexample by means of an electric motor, one of the supply terminals ofwhich is connected to a computer controlling the start-up of the engineaccording to given programs; the output shaft of the said engine formingthe input element of a mechanical transmission with elastic assistancemeans, the said transmission comprising an output element for example inthe form of a pusher acting on the piston of the sender. In every case,the piston defines, with the fixed body of the sender, a variable-volumechamber. When the sender is activated its piston is moved axially sothat the variable-volume chamber is pressurised, as well as the variablevolume chamber of the receiver 1, which increases in volume whilst thatof the sender decreases in volume.

When the sender is deactivated the chambers of the sender and receiverare depressurised, the chamber of the receiver decreasing in volumewhilst that of the sender increases in volume. There is therefore,during these operations, a transfer of control fluid from one chamber tothe other. It should be noted that the diaphragm, which in aconventional fashion has a friction clutch member, exerts a returnaction on the piston when the clutch is re-engaged; the chamber of thereceiver resuming its initial volume.

The control fluid can be gaseous in nature. It may for example becompressed air. Here the control fluid is hydraulic in nature andconsists of oil.

For simplicity the control will be referred to as a hydraulic control,whatever the nature of the fluid.

As is known the chamber of the receiver 1 is delimited by a fixed part 4and 5 and by a movable part 6 in cylinder/piston relationship.

The fixed part 4, 5 delimits a cavity 7 of annular shape into which thesupply inlet 3 opens out.

The movable part is a piston 6, annular in shape, movable axially insidethe cavity 7 in order to define, with the latter, the aforementionedvariable-volume chamber.

The cavity 7, as well as the said chamber, is therefore allowed to bepressurised and depressurised from the inlet 3 via the pipe 2.

Here the fixed part 4, 5 and the movable part 6—the piston 6—are coaxialwhilst being arranged concentrically. The receiver 1 is therefore of theconcentric type; the cavity 7 being blind, of axial orientation andannular.

More precisely the fixed part 4, 5 is here in two concentric parts 4, 5.

One of the parts, namely the external part 4, roughly of annular shapeand hereinafter referred to as the external body, has at its centre aroughly tubular front end portion 8 surrounding the other piece 5 in theform of a guide tube 5 and forming part of a protuberance 20, roughlytubular in shape. This tube 5 is metallic. It is thin in order to reducethe radial bulk and has an axis of axial symmetry X-X′.

The thickness of the tube 5 is less than the thickness of the tubularportion 8, with an axial length less than that of the tube 5.

The tube 5, here metallic, projects axially with respect to the tubularportion 8 and serves as a guide for the piston 6, which thus surroundsthe main part of the tube 5, whilst being surrounded by the tubularportion 8.

The piston 6 carries at its rear end a dynamic joint with lips 80. Thisjoint enters inside the cavity 7 and makes the latter fluidtight. Thefront end of the piston 6 acts on a clutch release bearing 9, whichconsists here of a ball bearing having a rotating race, forming a driveelement, suitable for acting on the diaphragm of the clutch, and anon-rotating race in connection with the piston 6. This piston 6 actsthrough its front end on the non-rotating race, separated from therotating race by balls.

Here the races of the bearing 9 are concentric and coaxial. This thrustbearing is carried by the piston 6 sliding axially along the metallictube 5.

The bearing 9 can be fixed radially whilst for example being a forcefit, through its non-rotating race, on the piston 6.

Here the bearing can move radially with respect to the piston 6 and thediaphragm of the clutch in order to reduce wear, knowing that the axisof axial symmetry of the diaphragm is not merged with that of thereceiver 1.

It is possible for the centring of the bearing 9 with respect to thediaphragm not to be maintained. For example, an element made of elasticmaterial, such as elastomer, can be interposed radially between thepiston 6 and the non-rotating race of the bearing. This element alsocouples the bearing to the piston.

Here a radial clearance exists between the front end of the piston 6 andthe bearing 9 and an axially acting elastic washer 10 couples thebearing to the piston 6. The bearing 9 can creep radially with respectto the piston until it finds its centring position with respect to thediaphragm. This centring is subsequently maintained by the elasticwasher 10. The clutch release bearing 9 is thus of the maintainedself-centring type.

The rotating race, here the external race, is profiled for local contactwith the diaphragm, more precisely for local contact with the internalend of the fingers of the latter.

Thus, when the internal end of the fingers of the diaphragm, centrallyopen, is curved in shape, the front face of the rotating race, intendedto cooperate with the said end, is roughly flat in shape.

When the internal end of the fingers of the diaphragm is flat, theexternal face of the rotating race is then curved.

Here the thrust bearing 9 is able to act in thrust on the internal end,depicted at 102 in FIG. 6, of the fingers of the diaphragm, theperipheral part of which, in the form of a Belleville washer, acts onthe thrust plate of the clutch in order normally to force the said platein the direction of the vehicle engine flywheel, forming a reactionplate, in order to clamp the friction linings of the clutch frictionmember between the said reaction and thrust plates fixed with respect torotation to the vehicle engine crankshaft.

This friction member, also referred to as a friction disc, has at itscentre a hub coupled rigidly or elastically to a disc carrying thefriction linings. The hub is fluted internally for its connection withrespect to rotation to a driven shaft, here the input shaft 100 of thegearbox. This shaft 100 passes through the guide tube 5 whilst beingsurrounded by it. The clutch is therefore normally engaged, the volumeof the variable chamber of the receiver 1 then being at a minimum. Areturn spring 11 is interposed axially between the portion 8 and theball bearing in order to maintain, in a known fashion, the rotating raceof the bearing 9 in permanent contact with the diaphragm in order toreduce wear. The torque of the drive shaft is therefore transmitted tothe input shaft of the gearbox.

In order to disengage the clutch, the cavity 7 of the receiver ispressurised as mentioned above, which causes an increase in volume ofthe chamber thereof and a movement of the piston 6 and of the thrustbearing 9 towards the left in FIG. 2.

The diaphragm, mounted pivotally on a cover fixed to the engineflywheel, tilts until its action on the thrust plate is cancelled out.The clutch is then disengaged since the friction linings of the clutchfriction member are then released.

The engine torque is then no longer transmitted to the input shaft ofthe gearbox having a casing 12. Naturally, the clutch can be equippedwith a device for taking up wear on the friction linings.

When the cavity 7 is depressurised, the diaphragm moves the clutchrelease bearing and piston towards the right in FIG. 2. The volume ofthe chamber of the receiver 1 is then at a minimum and the piston 6resumes its initial position. In this position, a residual pressureexists in the cavity 7.

The fixed part 4, 5 is intended to be fixed here to the front wall 12 ofthe fixed casing of the gearbox. The wall 12 has the input shaft 100 ofthe gearbox pass through it with the intervention of a joint 101,referred to as a rotating joint (visible more clearly in FIG. 6) betweenthe wall 12 and the input shaft as described below. This wall 12therefore has an opening for the passage of the input shaft. Thisopening is here large and is closed in FIGS. 1 to 4 by a ribbed plate 4provided with numerous holes 13 for fixing of the plate 4 to the wall 12by means of screws, the threaded body of which passes through the holes13 in order to come into engagement with female threads on the wall 12.

The heads of the screws bear on the front face of the plate 7, hereroughly ovoid in shape. This plate 4 serves as a closure plate for theopening in the wall 12 mentioned above.

According to one characteristic this plate 4 is used to integrate thisplate into the hydraulic receiver 1 and form the aforementioned externalbody 4 surrounding the guide tube 5.

Thus the protuberance 20 with its tubular portion 8, of axialorientation, is fixed to the plate. This protuberance 20 can be attachedby welding to the plate 4 with holes in it for passage of the inputshaft of the gearbox. Here the protuberance 20 is annular in shape andis in a single piece with the plate 4 made of castable material. Thisplate 4 is here based on aluminium. Advantage is taken of this, havingregard to the strength of the plate 4, to extend the latter, behind thewall 8, by means of a transverse flange 15 directed radially towards theinside and constituting the base of the blind cavity 7. This flange 15will be referred to as the internal flange and is thicker than the guidetube 5. It is directed radially towards the axis X-X′.

This arrangement makes it possible to limit the deformation of thecavity 7 under the effect of the pressure variations to which it issubject during the operations of disengaging and re-engaging the clutch.The movement of the piston 6 is thus more precise and accurate.

In addition the guide tube 5 and more precisely the means 16 ofconnecting it to the closure plate 4, as well as the static sealingjoint 17 of the cavity 7, are conserved. The joint 17 is toric in shape.

Here the connection means 16 consist of a fixing by crimping of a collar51, of transverse orientation, directed radially outwards, which theguide tube 5 has at its rear end.

These crimping means 16 are offset axially and radially with respect tothe sealing joint 17 acting between the internal periphery of theinternal flange 15, directed radially inwards, and the externalperiphery of the guide tube 5. Here the joint 17 is carried by theinternal flange 15 whilst being mounted in a sealing groove, notreferenced, which the said flange has at its internal periphery. Thisflange 15 is of low height and forms part of the aforementionedprotuberance 20, here in a single piece with the plate 4. The crimpingmeans 16 are offset towards the rear with respect to the sealing joint.

The tubular portion 8 constitutes the front part of this protuberance20, having at its external periphery two projections 18, 19 directedapproximately radially towards the outside.

The projections 18, 19 are provided with drillings, as can be seen inFIG. 2, extended in the mass of the protuberance in order to open out inthe base of the blind control cavity 7. The drillings therefore open outat the level of the front face of the flange 15, knowing that theprojections 18, 19 belong respectively to the feed inlet 3 and to thedrain circuit. The return spring 11 surrounds the tubular portion 8whilst being centred by it. A shoulder is formed at the junction of thetubular portion 8 with the main part of the protuberance 20 able here tohave the input shaft 100 of the gearbox pass through it.

This shoulder serves as a support for an end rim on a protective bellows21 surrounding the spring 11, in the form of a coil spring. The spring11 bears at one of its ends on the said rim. The other end of thebellows 21 is attached to a transverse disc 22 which the piston 6 has atits front end. The disc 22 is directed radially outwards and serves as asupport here, through its front face, for the non-rotating race of theclutch release bearing 9 and through its rear face on the other end ofthe spring 11.

As mentioned previously, a radial clearance exists between the piston 6and this non-rotating race, here the internal race the self-centringspring 10 consists (FIG. 3) of a Belleville washer bearing on the frontedge of the non-rotating race and on a connecting piece 23 made of sheetmetal, fitted on the internal periphery of a recess (not referenced)which the piston 6 has at its front end. This recess serves as a housingfor a scraper joint 150 surrounded by the piece 23 and bearing on aradial flange directed inwards, which the said piece 23 has at its rearend. At its front end the piece 23 has a radial flange directed outwardsfor the washer 10 to bear on.

The protuberance 20, internally hollow, therefore has on the inside afront portion, partly defining the cavity 7 open axially towards thefront, and a stepped rear portion, separated from each other by theinternal flange 15. This rear portion is stepped and is delimited on theinside by a first axially oriented cylindrical portion 24 and a secondaxially oriented portion 25 with a larger diameter.

The portion 24 is axially delimited to the front by the flange 15 and tothe rear by a transversely oriented flange 26 (FIG. 4) directed radiallyoutwards. The flange 26, referred to as the external flange, serves as asupport for the rear collar 51 of the guide tube 5. The flange 26therefore serves as an abutment shoulder for the collar 51. The guidetube 5 externally marries the shape of the first portion 24 and of therear face of the flange 15, whilst being in intimate contact with thesaid rear face.

The diameter of the main part of the tube 5 is therefore less than thatof its rear cylindrical portion 52. The portion.24 therefore forms abearing surface for the rear portion 52 of the tube 5.

From the rear end of the plate 4, the material issuing from the secondportion 25 of the protuberance 20 is pushed axially in a known fashionby means of a crimping tool, in order to form crimping sectors 16, withaxial immobilisation of the collar 51 between the shoulder 26 of theprotuberance 20 and the crimping sectors 16, in the form of annularsectors, knowing that, during this operation, the material creepsradially inwards. The collar 51 is also locked with respect to rotationunder the effect of the clamping force caused by the crimping.Naturally, in a variant, the crimping sectors 16 can form a continuousring.

It should be noted that the diameter of the first portion 24, forming abearing surface, is roughly equal to the external diameter of thetubular portion 8, whilst here being slightly greater than it.

In this way a much stronger crimping is obtained than the one describedin the document EP-A-0 168 932 since the hydraulic supply pressure inthe annular cavity 7 is exerted on the flange 15 so that the collar 51is conserved.

This makes the assembly of the guide tube 5 more reliable and stronger.The service life of this receiver is therefore increased, in a simpleand economical fashion, the metallic guide tube 5 being obtained easilyby the chasing of material, whilst the plate 8 made of castable materialis easily obtained by casting. The joint 17 is also conserved since thecrimping is not performed at this level, contrary to the arrangementdescribed in the document EP-A-0 168 932. The joint 16 is not crushedaxially.

The fluidtightness of the receiver 1 is therefore improved, whilst beingmore reliable. In addition the rear portion 52 of the tube 5 can serveas a centring surface for the joint shown diagrammatically at 101, incontact with the input shaft of the gearbox. The internal stepping ofthe rear portion of the tube 5 and of the plate 4 assists this.

It will be appreciated that the ribbed plate 4 is robust and thatincipient ruptures are very much reduced compared with a solution inwhich the receiver is fixed by lugs to the gearbox casing.

This is due to the large number of fixing holes 13. Naturally a sealingjoint (not visible) is interposed between the casing 12 and the plate 4,knowing that the plate 4 is fixed at the edge of the opening in thecasing 12 of the gearbox in order to close the said opening.

Naturally, as a variant, the gearbox can be replaced by anothertransmission box, for example with variable pulleys.

As a variant the connection means 16 can consist of a fixing of thecollar 51 to the abutment shoulder 26 by means of screws.

Any other assembly means can be envisaged.

As will have been understood, the external flange 26 delimits at thefront the second cylindrical portion 25 serving as a centring surfacefor the collar 51 whilst being in intimate contact with the externalperiphery of the collar 51.

In FIG. 2, the outlines of the chasing of material resulting in thebroadening of the second portion 25 can therefore be seen.

It should be noted that the plate 4 is provided with ribs (FIG. 1)connecting its protuberance to areas provided with fixing holes 13.

This fixing, as a variant, can be effected by riveting or by means ofbolts.

Naturally the presence of a large closure plate is not obligatory. Theplate 4 can be replaced by a smaller external body and the crimping canbe performed in the vicinity of the flange 15.

Thus, in FIG. 5, it is the external piece 4 of the fixed part 4, 5 whichis fixed to the casing of the gearbox, level with the aforementionedopening of the casing.

More precisely this piece 4 forms an external body approximately ofannular shape surrounding the internal guide tube 5. The body 4 has twolugs 130, only one of which is visible in FIG. 5, for fixing it to thewall of the gearbox casing, usually by means of screws each passingthrough an opening 131 on each lug. A third fixing point is alsoprovided, whose the passage hole can be seen at 131.

The rear of the body 4 is roughly in the form of a plate 120 of smallersize than the plate 4 in FIG. 1, from which the front tubular portion 8of which is formed by casting. The body 4, made of castable material, isfor example based on aluminium.

The lugs 130 form part of the plate 120 with three fixing points andextend for the major part radially outwards.

According to one characteristic this is taken advantage of, havingregard to the strength of the body 4, in order to extend the latter, tothe rear of the wall 8 and of the plate 120, by means of a transverseflange 15 directed radially inwards, constituting the base of the blindcavity 7. This flange 15, referred to as the internal flange, belongs toa rear tubular section 121 extending to the rear of the plate 120. Theflange 15, directed radially towards the axis X-X′, is thicker than thetube 5.

The flange 15 makes it possible to limit the deformation of the cavity 7under the effect of the pressure variations to which it is subjectduring the operations of disengaging and re-engaging the clutch. Themovement of the piston 6 is thus more precise and accurate.

In addition the tube 5 is conserved and more precisely the means 16 ofconnecting it to the body 4, as well as the static sealing joint 17 forthe cavity 7. This joint 17 is here toric in shape, whilst being axiallyoblong in shape for good contact with the tube 5 and a good seal.

Here the connection means 16 consist of fixing by crimping.

More precisely, the rear section 121 is notched, as in FIG. 2, forhousing the joint 121 and delimiting the flange 15. A connecting groove32 is produced at the rear of the flange 15 and the metal of the tube 5is caused to creep inside the groove 32, here of semicircular section,favourable to good fixing. The thickness of the tube 5 makes thispossible. It should be noted that the tube 101 bears here, unlike FIG.2, directly on the face of the flange 15 turned in the oppositedirection to the cavity 7. By virtue of this method of connection, incombination of the flange 15, the tube is simple in shape and does nothave, at the rear, a transverse collar for fixing it by crimping it tothe body 4. Material is saved on. The tube 5 being of purely tubularshape.

The tube 5 undergoes very slight deformations under the effect of thepressure variations in the cavity 7. The piston 6 moves under goodconditions.

These crimping means 16 are offset axially towards the rear with respectto the sealing joint 17 acting between the internal periphery of theflange 15, directed radially inwards, and the external periphery of theguide tube 5. Here the joint 17 is carried by the internal flange 15,whilst being mounted in a splayed sealing groove, not referenced, whichthe said flange has at its internal periphery. The sealing groove issplayed radially inwards in the direction of the axis X-X′ and axiallyis wider than the connecting groove 32. This flange 15 is of low heightand forms part of the rear part of the body 4, whose plate 120 ispierced in order to form the supply inlet 3 opening out in the base ofthe cavity 7. The pipe 2 is attached by screwing its flange to the topedge of the plate 120, in line with the inlet 3. The crimping means16—local creep of the tube 5 in the groove 32—are located axiallybetween the joints 17 and 101. It will be noted that the solution issimpler than the one in FIGS. 1 and 2 since the duct 5 is produced inthe thickness of the plate 120.

The preloading spring 11 surrounds the tubular portion 8 whilst beingcentred by it. A shoulder 105 is formed at the junction of the tubularportion 8 with the plate 120 suitable for having the shaft lo passthrough it.

It should be noted that the body 4 does not have any drainage duct, thisbeing produced at the external peripher of the pipe 2 at 119.

More precisely, the pipe 2 extends outside of the gearbox casing andpasses through the said casing. This pipe has, outside the said casing,a tubular protuberance 119 serving to effect the drainage. Thisprotuberance is normally covered by a protective cap 118. The pipe hasan external end 117 shaped as a plug-in female connector with a pin 116engagled in slots in the end 117 in order to receive the male connectorof a conduit coming from the sender.

The pipe 2 has a right-angled shape with a vertical part fixed to theplate 120 and a roughly horizontal part extending outside the gearboxcasing and carrying the drain 119 and the end coupling. Here the pipe 2has a flange with laterally two holes for screws to pass for fixing theflange to the external edge of the plate 120 (FIG. 5). Naturally thepipe 2 can be attached by broaching or screwing to the body 4. Theshoulder 105 serves as a support for an end rim which is, as in FIG. 2,on a protective bellows 21 surrounding the spring 11, in the form of acoil spring. The spring 11 bears at one of its ends on the said rim bymeans of a metallic support piece 123 interposed between the spring andthe rim. The piece 123 has two transverse parts connected to each otherby a roughly horizontal part. One of the transverse parts is in contactwith the end rim radially above the other transverse part in contactwith the spring 11 centred by means of a thicker part, on the rear endof the front tubular portion 8.

The other end of the bellows 21 is attached to a metallic bearing andsupport piece 122, referred to as a carrier piece 122, annular in shape.

The carrier piece 122 is here made of sheet metal and carries theelastic washer 10, usually referred to as a self-centring washer, thebearing 9 and the front end rim on the bellows 21.

The piece 122 is embedded (anchored) partly in the piston 6 made ofsynthetic material, here made of plastic material reinforced withfibres. The piston 6 can for example be based on “Delrin” or can be madefrom any other material having good slip qualities. At the front of thepiston 6, the scraper joint 150 is provided in order, in a knownfashion, to avoid contaminating the friction linings of the frictiondisc.

The piece 122 has, in order to do this, holes for its firm anchoring inthe piston 6 by the moulding-on technique. The piece 122 is thereforefixed by moulding onto the piston 6 made of synthetic material. Thepiece 122 carries the washer 10, the joint 150, the ball bearing 9, theexternal race of which cooperates with the end 102 of the fingers of thediaphragm, the end of the bellows 21 and of the preloading spring 11.The piece serves as an abutment for the internal edge of the bearing 9in the shape of a flag and fluidtight.

In FIG. 6, the dynamic sealing joint can be seen at 80. Naturally thepiece 122 can be attached by snapping onto the piston 6. It will beappreciated that the bearing 9 extends for a major part above the piece122 whilst being directed axially towards the plate 120 in order toreduce the axial dimension.

As a variant, the means 16 of connecting the tube 5 to the body 4 canhave another form. Thus, in FIG. 8, the joint 17 is mounted in thebottom of a trapezoidal-shaped connecting and sealing groove 132section. The local upsetting of material 116 of the tube 5 is effecteddirectly in this groove 132.

The joint 17 is compressed between the upsetting 116, directed in theopposite direction to the axis X-X′ and the bottom of the groove 132. Inthis case the machinings of the flange 15 are reduced.

As a variant, FIGS. 9 and 10, the joint 17 is, as in FIG. 6, placed in aspecial connecting groove 332 less broad axially than the sealinggroove. The connection is effected by means of a circlip 226 corrugatedradially and open, mounted in a radial connecting groove 332 of oblongshape formed in the flange 15 and in a groove 333 formed incorrespondence with the rear end of the tube 5. This groove 333 leads tothe local upsetting of the tube 5 towards the inside in a similar mannerin order to form the groove 153. Thus the connection of the tube 5 wit hthe body 5 is effected by snapping on, the circlip being placed inadvance in the groove 332. This circlip 226 is elastically deformableradially inwards in order to close up and then relax and fall into thegroove 333 when the tube 5 is connected with the body 4.

The internal tube 5 therefore has a symmetrical shape, this tube havinga groove (not referenced in FIG. 6) at one end for mounting a circlip.This groove has the same shape as the groove S33. Naturally the joint 80has an external lip for contact with the internal periphery of theportion 8 of the body 4 and an internal lip for contact with theexternal periphery of the tube 5.

Naturally the external body can be mounted indirectly on the fixedstructure, via the gearbox casing, by means of an adapter sole plate asdescribed for example in the document FR-A-2 745 616.

In this case, the external body is standard and it is the sole platewhich carries the fixing lugs for the connecting means of the bayonettype, acting between the sole plate land the external body. The clutchrelease bearing can have, reversing the structures, a rotating internalrace and a non-rotating external race, provided with an internal flange,intended to bear, under the action of the elastic self-centring washer,against the transverse support section on the carrier piece 122.

As is clear from the description of the drawings, the internal flange15, advantageously obtained by casting, is thicker than the guide tube5. The connecting means 16 can be drimping or snapping-on means and makeit possible to fix the guide tube 5 to the internal flange 15. Theconnecting grooves 32, 132, 332 for the internal flange open out at theinternal periphery of the flange 15.

The external body 4 can be made from mouldable synthetic material, suchas plastic material reinforced with fibres.

The circlip in FIG. 6 forms a stop for the piston 6. This stop can haveanother shape.

It should be noted that the control fluid, here oil, enters the cavity 7under very good conditions. This is because, in all the figures, theinlet 3, in the form of a duct, opens out at the top part of the frontface of the internal flange 15. This top part forms a recess (a notch),rounded in shape and extended by an inclined face.

The internal bore of the portion 8 is also notched at its rear part atthe inlet 3. This makes it possible to carry out lapping and prevent thetop lip of the joint 80 coming into contact with the flange 15. Therecessing of the front face of the flange 18, delimiting the cavity 7,therefore also affects the rear end of the internal periphery of thefront portion 8.

Naturally the tube 5 can, as in FIGS. 1 to 4, have an end plate 215,directed radially in the opposite direction to the axis X-X′ and crimpedat 216 in contact with the rear transverse face 115 of the flange 15turned in the opposite direction to the cavity 7. The tube does not haveany end collar.

The crimping 216 is here of the axial type, the material of the rearsection 121 being crushed axially for preferably forming crimpingsectors as in the embodiment in FIGS. 1 to 4. It is not the material ofthe tube which creeps and material is saved on compared with theembodiments in FIG. 2.

Naturally, FIG. 12, the static joint 117 can be located in a groove (notreferenced) formed in the transverse face 115, a radial clearance existsbetween the tube 5, the flange 215 of which is crimped as in FIG. 11,and the internal periphery of the flange 15.

In a variant (FIG. 13) the flange 15 has, at its internal periphery, acollar 315 extending its face 115.

The tube 5 has a reduction in thickness at its end adjacent to thecollar 315 in order to form a shoulder formed by means of the reductionin thickness and cooperating with the front face of the collar 315turned towards the cavity 7. Afterwards, the material of the free end ofthe guide tube 5 in contact with the rear face of the collar 315 isfolded, for fixing the tube 5 to the collar 315 by crimping, the joint17 being mounted in a sealing groove as in FIGS. 1 and 16.

Naturally, the different embodiments can be combined together, therotating joint not necessarily being carried by the external body.

Thus the connecting modes in FIGS. 6 to 10 can be effected in the rearface 115 of the internal flange 15.

This face can therefore have a distinct connecting groove and not asealing groove, the material of the flange 215 being upset inside theconnecting groove preferably splayed in the opposite direction to thecavity 7.

In this way a good locking of the tube 5 with respect to rotation isobtained by virtue of the splaying of the connecting groove possiblyalso forming the sealing groove.

In order to prevent the plate 215 escaping axially in the oppositedirection to the cavity, the plate 215 is locked axially by means, forexample, of a circlip engaged in a groove in the body in order to gripthe plate 215 between the face 115 and the circlip. Advantageously, theconnecting groove is located radially above the sealing groove. As avariant, the body 4 is threaded internally at the rear for mounting anexternally threaded washer. This washer forms a nut for gripping theplate between the face 115 and the said nut.

As a variant, it is possible to use an intermediate piece crimped asdescribed in the document FR-96 11888, filed on Nov. 30, 1996, in orderto effect the axial fixing.

Naturally, the plate 215 can be bonded to the face 115 notably when thebody 4 is made from plastic material.

What is claimed is:
 1. A hydraulic receiver (1) for clutch controlhaving a fixed part (4, 5) comprising a metallic internal guide tube (5)with an axial axis of symmetry (X-X′) and a concentric external body (4)defining a blind annular cavity (7) able to be supplied with fluid andinside which there is mounted, so as to be axially movable, a piston (6)carrying a drive element (9) suitable for acting on a clutch, in whichthe base of the blind cavity (7) comprises an internal flange (15), onthe external body (4), directed towards the axial axis of symmetry(X-X′) of the guide tube (5), said internal flange (15) being thickerthan the guide tube (5), wherein a static sealing joint acts between theinternal flange (15) and the guide tube (5) whilst being mounted in asealing groove, and wherein connecting means (16, 116) act between theinternal flange (15) and the guide tube (5) in order to fix the guidetube to the external body (4), said connecting means (16) including aconnecting groove (32, 132, 332) formed in the internal flange (15),wherein said sealing groove (132) is formed in the internal flange (15)and is merged with the connecting groove (132).
 2. Receiver according toclaim 1, wherein the connecting means (16) consist of crimping means andin that the material of the guide tube (5) is upset locally in theconnecting groove (32, 132).
 3. Receiver according to claim 1, whereinthe sealing joint (17) is interposed between the base of the connectinggroove and the local upsetting of material of the guide tube (5). 4.Receiver according to claim 1, wherein the connecting means (16) actbetween the external periphery of the guide tube (5) and the internalperiphery of the internal flange (15).
 5. Receiver according to claim 1,wherein a static sealing joint (17) acts between the internal peripheryof the internal flange (15) and the external periphery of the guide tube(5).
 6. A hydraulic receiver (1) for clutch control having a fixed part(4, 5) comprising a metallic internal Guide tube (5) with an axial axisof symmetry (X-X′) and a concentric external body (4) defining a blindannular cavity (7) able to be supplied with fluid and inside which thereis mounted, so as to be axially movable, a piston (6) carrying a driveelement (9) suitable for acting on a clutch, wherein the base of theblind cavity (7) comprises an internal flange (15), on the external body(4), directed towards the axial axis of symmetry (X-X′) of the guidetube (5), said internal flange (15) being thicker than the guide tube(5), wherein a static sealing joint acts between the internal flange(15) and the guide tube (5), and wherein connecting means (16, 116) actbetween the internal flange (15) and the guide tuble (5) in order to fixthe guide tube to the external body (4), wherein the connecting meanscomprise an elastically deformable member.
 7. Receiver according toclaim 6, wherein the connecting means include an open annulus ofcorrugated shape (270) radially engaged in an oblong connecting groove(332) formed in the internal flange and in a facing groove formed in theguide tube (5) at one of its axial ends.
 8. Receiver according to claim1, characterised in that the piston is made from synthetic material andslides directly on the guide tube (5).